Triphenylene silane hosts

ABSTRACT

Novel aryl silicon and aryl germanium host materials, and in particular host materials containing triphenylene and pyrene fragments, are described. These compounds improve OLED device performance when used as hosts in the emissive layer of the OLED.

The claimed invention was made by, on behalf of, and/or in connectionwith one or more of the following parties to a joint universitycorporation research agreement: Regents of the University of Michigan,Princeton University, The University of Southern California, and theUniversal Display Corporation. The agreement was in effect on and beforethe date the claimed invention was made, and the claimed invention wasmade as a result of activities undertaken within the scope of theagreement.

FIELD OF THE INVENTION

The present invention relates to compounds suitable for use as hostmaterials in OLEDs, specifically compounds comprising arylgermane andarylsilane groups.

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting devices (OLEDs), organic phototransistors, organic photovoltaiccells, and organic photodetectors. For OLEDs, the organic materials mayhave performance advantages over conventional materials. For example,the wavelength at which an organic emissive layer emits light maygenerally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full colordisplay. Industry standards for such a display call for pixels adaptedto emit particular colors, referred to as “saturated” colors. Inparticular, these standards call for saturated red, green, and bluepixels. Color may be measured using CIE coordinates, which are wellknown to the art.

One example of a green emissive molecule istris(2-phenylpyridine)iridium, denoted Ir(ppy)₃, which has the followingstructure:

In this, and later figures herein, we depict the dative bond fromnitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled inthe art, a first “Highest Occupied Molecular Orbital” (HOMO) or “LowestUnoccupied Molecular Orbital” (LUMO) energy level is “greater than” or“higher than” a second HOMO or LUMO energy level if the first energylevel is closer to the vacuum energy level. Since ionization potentials(IP) are measured as a negative energy relative to a vacuum level, ahigher HOMO energy level corresponds to an IP having a smaller absolutevalue (an IP that is less negative). Similarly, a higher LUMO energylevel corresponds to an electron affinity (EA) having a smaller absolutevalue (an EA that is less negative). On a conventional energy leveldiagram, with the vacuum level at the top, the LUMO energy level of amaterial is higher than the HOMO energy level of the same material. A“higher” HOMO or LUMO energy level appears closer to the top of such adiagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled inthe art, a first work function is “greater than” or “higher than” asecond work function if the first work function has a higher absolutevalue. Because work functions are generally measured as negative numbersrelative to vacuum level, this means that a “higher” work function ismore negative. On a conventional energy level diagram, with the vacuumlevel at the top, a “higher” work function is illustrated as furtheraway from the vacuum level in the downward direction. Thus, thedefinitions of HOMO and LUMO energy levels follow a different conventionthan work functions.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

SUMMARY OF THE INVENTION

In one aspect, a compound having the Formula I is provided:

In the compound of Formula I, Ar and Ar′ are independently selected fromthe group consisting of phenyl, biphenyl, naphthalene, dibenzothiopheneand dibenzofuran, which are optionally further substituted. Z isselected from Si and Ge. L is a single bond or comprises an aryl orheteroaryl group having from 5-20 carbon atoms, which is optionallyfurther substituted. A is a group directly bonded to Z and is selectedfrom the group consisting of triphenylene, tetraphenylene, pyrene,naphthalene, fluoranthene, chrysene, phenanthrene, azatriphenylene,azatetraphenylene, azapyrene, azanaphthalene, azafluoranthene,azachrysene, azaphenanthrene, and combinations thereof, which areoptionally further substituted with one or more groups selected from thegroup consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, aryl, aryloxy, and combinations thereof.

B contains a group selected from the group consisting of carbazole,dibenzofuran, dibenzothiophene, dibenzoselenophene, aza-carbazole,aza-dibenzofuran, aza-dibenzothiophene, azadibenzoselenophene, andcombinations thereof, which are optionally further substituted with oneor more groups selected from hydrogen, deuterium, halide, alkyl,cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl,alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl,carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof, and wherein thesubstitution is optionally fused to the carbazole, dibenzofuran,dibenzothiophene, dibenzoselenophene, aza-carbazole, aza-dibenzofuran,aza-dibenzothiophene or azadibenzoselenophene group.

In one aspect, A is

wherein K₁ to K₁₂ are independently selected from N and C—R′, andwherein R′ is selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, aryl, aryloxy, andcombinations thereof.

In one aspect, B is selected from the group consisting of:

wherein X₁-X₁₅ are independently selected from the group consisting of Nand C—R″, wherein R″ is selected from a group consisting of hydrogen,deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy,aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof, and wherein Y₁ and Y₂ are independently selected from the groupconsisting of O, S, and Se.

In one aspect, A is selected from the group consisting of:

In one aspect, A is selected from the group consisting of:

In one aspect, B is selected from the group consisting of:

wherein Y₁ is selected from the group consisting of O, S, and Se,wherein R is selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfanyl, sulfonyl, phosphino, and combinationsthereof.

In one aspect, L is independently selected from the group consisting of:

In one aspect, A is tripheynylene. In another aspect, A is pyrene. Inone aspect, Ar and Ar′ are phenyl. In one aspect, L is phenyl.

In one aspect, the compound is selected from the group consisting ofCompound 1-Compound 35.

In one aspect, a first device is provided. The first device comprises anorganic light-emitting device, which further comprises an anode, acathode, and an organic layer, disposed between the anode and thecathode, comprising a compound having the Formula I:

In the compound of Formula I, Ar and Ar′ are independently selected fromthe group consisting of phenyl, biphenyl, naphthalene, dibenzothiopheneand dibenzofuran, which are optionally further substituted. Z isselected from Si and Ge. L is a single bond or comprises an aryl orheteroaryl group having from 5-20 carbon atoms, which is optionallyfurther substituted. A is a group directly bonded to Z and is selectedfrom the group consisting of triphenylene, tetraphenylene, pyrene,naphthalene, fluoranthene, chrysene, phenanthrene, azatriphenylene,azatetraphenylene, azapyrene, azanaphthalene, azafluoranthene,azachrysene, azaphenanthrene, and combinations thereof, which areoptionally further substituted with one or more groups selected from thegroup consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, aryl, aryloxy, and combinations thereof.

B contains a group selected from the group consisting of carbazole,dibenzofuran, dibenzothiophene, dibenzoselenophene, aza-carbazole,aza-dibenzofuran, aza-dibenzothiophene, azadibenzoselenophene, andcombinations thereof, which are optionally further substituted with oneor more groups selected from hydrogen, deuterium, halide, alkyl,cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl,alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl,carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof, and wherein thesubstitution is optionally fused to the carbazole, dibenzofuran,dibenzothiophene, dibenzoselenophene, aza-carbazole, aza-dibenzofuran,aza-dibenzothiophene or azadibenzoselenophene group.

In one aspect, the organic layer is an emissive layer and the compoundof Formula I is a host. In another aspect, the organic layer furthercomprises an emissive dopant.

In one aspect, the emissive dopant is a transition metal complex havingat least one ligand selected from the group consisting of:

wherein R_(a), R_(b), and R_(c) may represent mono, di, tri or tetrasubstitutions, wherein R_(a), R_(b), and R_(c) are independentlyselected from the group consisting of hydrogen, deuterium, halide,alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl,acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein twoadjacent substituents of R_(a), R_(b), and R_(c) are optionally joinedto form a fused ring.

In one aspect, the emissive dopant has the formula

wherein D is a 5- or 6-membered carbocyclic or heterocyclic ring,wherein R₁, R₂, and R₃ independently represent mono, di, tri or tetrasubstitution, wherein each of R₁, R₂, and R₃ are independently selectedfrom the group consisting of hydrogen, deuterium, halide, alkyl,cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl,alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl,carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof, wherein R₁ canbe optionally linked to ring D, wherein n is 1, 2, or 3, and wherein X—Yis another ligand.

In one aspect, the device further comprises a second organic layer thatis a non-emissive layer and the compound having Formula I is a materialin the second organic layer.

In another aspect, the second organic layer is a blocking layer and thecompound having Formula I is a blocking material in the second organiclayer. In one aspect, the second organic layer is an electrontransporting layer and the compound having the Formula I is an electrontransporting material in the second organic layer.

In one aspect, the first device is a consumer product. In anotheraspect, the first device is an organic light-emitting device. In oneaspect, the first device comprises a lighting panel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer.

FIG. 3 shows a compound of Formula I.

FIG. 4 shows an example device that incorporates compounds of Formula I.

FIG. 5 shows the differential scanning calorimetry scans for selectedcompounds of Formula I and for selected comparative compounds.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporatedby reference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 1 shows an organic light emitting device 100. The figures are notnecessarily drawn to scale. Device 100 may include a substrate 110, ananode 115, a hole injection layer 120, a hole transport layer 125, anelectron blocking layer 130, an emissive layer 135, a hole blockinglayer 140, an electron transport layer 145, an electron injection layer150, a protective layer 155, and a cathode 160. Cathode 160 is acompound cathode having a first conductive layer 162 and a secondconductive layer 164. Device 100 may be fabricated by depositing thelayers described, in order. The properties and functions of thesevarious layers, as well as example materials, are described in moredetail in U.S. Pat. No. 7,279,704 at cols. 6-10, which are incorporatedby reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F.sub.4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,a cathode 215, an emissive layer 220, a hole transport layer 225, and ananode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2.For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

Unless otherwise specified, any of the layers of the various embodimentsmay be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 toForrest et al., which is incorporated by reference in its entirety, anddeposition by organic vapor jet printing (OVJP), such as described inU.S. patent application Ser. No. 10/233,470, which is incorporated byreference in its entirety. Other suitable deposition methods includespin coating and other solution based processes. Solution basedprocesses are preferably carried out in nitrogen or an inert atmosphere.For the other layers, preferred methods include thermal evaporation.Preferred patterning methods include deposition through a mask, coldwelding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819,which are incorporated by reference in their entireties, and patterningassociated with some of the deposition methods such as ink-jet and OVJD.Other methods may also be used. The materials to be deposited may bemodified to make them compatible with a particular deposition method.For example, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processability than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the invention maybe incorporated into a wide variety of consumer products, including flatpanel displays, computer monitors, medical monitors, televisions,billboards, lights for interior or exterior illumination and/orsignaling, heads up displays, fully transparent displays, flexibledisplays, laser printers, telephones, cell phones, personal digitalassistants (PDAs), laptop computers, digital cameras, camcorders,viewfinders, micro-displays, vehicles, a large area wall, theater orstadium screen, or a sign. Various control mechanisms may be used tocontrol devices fabricated in accordance with the present invention,including passive matrix and active matrix. Many of the devices areintended for use in a temperature range comfortable to humans, such as18 degrees C. to 30 degrees C., and more preferably at room temperature(20-25 degrees C.).

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures.

The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl,heterocyclic group, aryl, aromatic group, and heteroaryl are known tothe art, and are defined in U.S. Pat. No. 7,279,704 at cols. 31-32,which are incorporated herein by reference.

In one embodiment, a compound having the Formula I is provided:

In the compound of Formula I, Ar and Ar′ are independently selected fromthe group consisting of phenyl, biphenyl, naphthalene, dibenzothiopheneand dibenzofuran, which are optionally further substituted. Z isselected from Si and Ge. L is a single bond or comprises an aryl orheteroaryl group having from 5-20 carbon atoms, which is optionallyfurther substituted. A is a group directly bonded to Z and is selectedfrom the group consisting of triphenylene, tetraphenylene, pyrene,naphthalene, fluoranthene, chrysene, phenanthrene, azatriphenylene,azatetraphenylene, azapyrene, azanaphthalene, azafluoranthene,azachrysene, azaphenanthrene, and combinations thereof, which areoptionally further substituted with one or more groups selected from thegroup consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, aryl, aryloxy, and combinations thereof.

B contains a group selected from the group consisting of carbazole,dibenzofuran, dibenzothiophene, dibenzoselenophene, aza-carbazole,aza-dibenzofuran, aza-dibenzothiophene, azadibenzoselenophene, andcombinations thereof, which are optionally further substituted with oneor more groups selected from hydrogen, deuterium, halide, alkyl,cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl,alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl,carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof, and wherein thesubstitution is optionally fused to the carbazole, dibenzofuran,dibenzothiophene, dibenzoselenophene, aza-carbazole, aza-dibenzofuran,aza-dibenzothiophene or azadibenzoselenophene group.

An “aryl” group is an aromatic all carbon group, which can contain oneor more fused rings within it. Merely by way of example, and without anylimitation, exemplary aryl groups can be phenyl, naphthalene,phenanthrene, corannulene, etc. A “heteroaryl” group is an “aryl” groupcontaining at least one heteroatom. Merely by way of example, andwithout any limitation, exemplary heteroaryl groups can be pyridine,quinoline, phenanthroline, azacorannulene, etc. Both “aryl” and“heteroaryl” groups can have multiple attachment points connecting themto other fragments.

The “aza” designation in the fragments described above, i.e.aza-dibenzofuran, aza-dibenzonethiophene, etc. means that one or more ofthe C—H groups in the respective fragment can be replaced by a nitrogenatom, for example, and without any limitation, azatriphenyleneencompasses both dibenzo[f,h]quinoxaline and dibenzo[f,h]quinoline. Oneof ordinary skill in the art can readily envision other nitrogen analogsof the aza-derivatives described above, and all such analogs areintended to be encompassed by the terms as set forth herein.

It is to be understood that when a molecular fragment is described asbeing a substituent or otherwise attached to another moiety, its namemay be written as if it were a fragment (e.g. naphthyl, dibenzofuryl) oras if it were the whole molecule (e.g. naphthalene, dibenzofurna). Asused herein, these different ways of designating a substituent orattached fragment are considered to be equivalent.

As used herein, fragments containing the following structure:

are called DBX groups, i.e. dibenzo X₁, where X₁ is any of the atoms orgroups described herein. In the DBX group, A₁-A₈ can comprise carbon ornitrogen.

The novel compounds disclosed herein contain two distinctly differentgroups, polycyclic aromatic hydrocarbon, such astriphenylene/pyrene-based group A, and DBX- or carbazole-based group B,connected with a silane or germane spacer, resulting in an asymmetricstructure. These compounds have a number of advantageous properties whenused in OLED devices. Firstly, triphenylene and pyrene have excellentcharge-transport capabilities, while DBX and carbazole have appropriateLUMO and HOMO levels, for electron and hole injection from adjacentlayers. The combination of triphenylene/pyrene and DBX or carbazoleresults in compounds favorable for both charge injection and transport.Further derivatization on these groups can maintain, and even improve,the excellent charge injection and transport characteristics. Secondly,the silane and germane spacers break the conjugation between groups Aand B, retaining the high triplet energies of the individual groups inthe entire molecule, and thus effectively reducing quenching andallowing for the use of compounds of Formula I with high triplet energyemitters.

The compounds of Formula I have additional advantages over knownsymmetric analogs because compounds of Formula I are less prone tocrystallization. As a result, compounds of Formula I possess improvedfilm uniformity, which, without being bound by theory, is believed to bea result of reduction in phase separation between the emitters and hostmaterials in OLEDs. The novel compounds of Formula I can be used toimprove OLED device performance parameters, such as emission spectrumline shape, efficiency and lifetime. Furthermore, compounds of Formula Ialso tend to be soluble in organic solvents such as toluene, xylene, and3-phenoxytoluene, and are amenable to solution processing which ishighly desirable for low-cost lighting applications.

In one embodiment, A is

wherein K₁ to K₁₂ are independently selected from N and C—R′, andwherein R′ is selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, aryl, aryloxy, andcombinations thereof.

In one embodiment, B is selected from the group consisting of:

wherein X₁-X₁₅ are independently selected from the group consisting of Nand C—R″, wherein R″ is selected from a group consisting of hydrogen,deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy,aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof, and wherein Y₁ and Y₂ are independently selected from the groupconsisting of O, S, and Se. The dashed lines in the chemical structuresdisclosed herein represent a bond through any position on that groupcapable of forming a single bond with another atom.

In one embodiment, A is selected from the group consisting of:

In one embodiment, A is selected from the group consisting of:

In one embodiment, B is selected from the group consisting of:

wherein Y₁ is selected from the group consisting of O, S, and Se,wherein R is selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof.

In one embodiment, L is independently selected from the group consistingof:

In one embodiment, A is tripheynylene. In another embodiment, A ispyrene. In one embodiment, Ar and Ar′ are phenyl. In one embodiment, Lis phenyl.

In one embodiment, the compound is selected from the group consistingof:

The structures of the Comparative Compounds described herein are asfollows:

Table 1 lists the triplet energy levels for Compound 1-4 and ComparativeCompounds CC-1 and CC-3. The triplet energy was measured from themaximum of the highest energy 0-0 vibronic band of the phosphorescencespectra collected in 10⁻⁴ M solution of the corresponding compound in2-methyltetrahydrofuran at 77 K. While comparative compound CC-3, wheretriphenylene is connected with dibenzothiophene through a benzene unit,has a triplet energy of 2.64 eV, Compound 1 of Formula I, where a silaneunit is inserted between triphenylene and the rest of the aromaticsystem, has a much higher triplet energy of 2.86 eV. This suggests thatintroduction of silane group is able to maintain a high triplet energyof triphenylene. This is also supported by the results of Compounds 2-4and CC-1. A high triplet energy is required for the host materials toaccommodate blue phosphorescent emitters.

TABLE 1 Selected Triplet Energy Levels for Compounds of Formula I andComparison Compounds Compound Triplet energy, eV Compound 1 2.86Compound 2 2.86 Compound 3 2.86 Compound 4 2.86 CC-1 2.88 CC-3 2.64

Table 2 lists the HOMO/LUMO energy levels for selected compounds ofFormula I and Comparative Compound CC-1. The HOMO/LUMO levels weremeasured by differential pulse voltammetry in DMF solutions at aconcentration of 10⁻³ M, with 0.1 M tetrabutylammoniumhexafluorophosphate as the supporting electrolyte. A glass carbon disk,a platinum wire and a silver wire are used as the working, counter andpseudo reference electrodes, respectively. Ferrocene is added into thesolution to serve as the internal standard for each measurement. Theresultant oxidation potential (E_(ox)) and reduction potential(E_(red)), adjusted to ferrocene, are used to calculate the HOMO/LUMOlevels as −4.8 eV−qE_(ox) and −4.8 eV−qE_(red), respectively, where q isthe electron charge. All compounds have LUMO levels at about −2.1 eV,suitable for electron injection from adjacent electron transport layers.Though comparative compound CC-1 has a HOMO level below −6.00 eV, whichis the measurement limit, the HOMO levels for compounds of Formula Icould be tuned through variation of B group. Indeed, the HOMO levels ofCompounds 3, 4 and 5 were found to be −5.67, −5.55 and −5.41 eV,respectively. It is noted that these HOMO levels are below commonly usedtriplet emitters, allowing efficient hole trapping in the deviceoperation.

TABLE 2 Selected HOMO/LUMO Energy Levels for Compounds of Formula I andComparison Compounds Compound HOMO, eV LUMO, eV Compound 1 <−6.00 −2.08Compound 2 <−6.00 −2.06 Compound 3 −5.67 −2.08 Compound 4 −5.55 −2.07Compound 5 −5.41 −2.04 CC-1 <−6.00 −2.05

FIG. 5 shows the differential scanning calorimetry (DSC) curves forselected compounds of Formula I and for Comparative Compounds CC-1 andCC-2. Samples were thermally vaporized under vacuum at a pressure lessthan 10⁻⁵ Torr and condensed in a zone 100° C. cooler than thevaporization zone. The condensed samples were gradually cooled to roomtemperature before subjecting to DSC measurement where the reportedfirst heating scans were recorded at 10° C./min under nitrogenatmosphere. With asymmetric structures, compounds of Formula I areamorphous with stable morphological stability. During heating from 30°C. to 330° C., Compounds 1, 3 and 4 undergo glass transitions at 103,101, and 144° C., respectively, without encountering any crystallizationor melting. Compound 2 shows a small melting peak at 212° C. with asmall melting enthalpy of 2 J/g due to residual crystals embedded in anamorphous bulk. On the other hand, CC-1 with a symmetric structureencounters a pronounced melting peak at 243° C. with a melting enthalpyof 58 J/g, suggesting the presence of significant crystals. Furthermore,CC-2 comprising a simple triphenylsilyl group attached to triphenyleneis highly crystalline with a melting peak at 207° C. accompanied by amelting enthalpy of 75 J/g. In fact, CC-2 does not undergo any glasstransition during the first heating scan, suggesting the absence ofamorphous phase and complete crystallinity. These DSC resultsdemonstrated that the asymmetric structure according to this inventionis effective in suppressing crystallization and is conducive to a stableamorphous morphology, which is beneficial to device operationalstability.

In one embodiment, a first device is provided. The first devicecomprises an organic light-emitting device, which further comprises ananode, a cathode, and an organic layer, disposed between the anode andthe cathode, comprising a compound having the Formula I:

In the compound of Formula I, Ar and Ar′ are independently selected fromthe group consisting of phenyl, biphenyl, naphthalene, dibenzothiopheneand dibenzofuran, which are optionally further substituted. Z isselected from Si and Ge. L is a single bond or comprises an aryl orheteroaryl group having from 5-20 carbon atoms, which is optionallyfurther substituted. A is a group directly bonded to Z and is selectedfrom the group consisting of triphenylene, tetraphenylene, pyrene,naphthalene, fluoranthene, chrysene, phenanthrene, azatriphenylene,azatetraphenylene, azapyrene, azanaphthalene, azafluoranthene,azachrysene, azaphenanthrene, and combinations thereof, which areoptionally further substituted with one or more groups selected from thegroup consisting of hydrogen, deuterium, halide, alkyl, cycloalkyl,heteroalkyl, arylalkyl, aryl, aryloxy, and combinations thereof.

B contains a group selected from the group consisting of carbazole,dibenzofuran, dibenzothiophene, dibenzoselenophene, aza-carbazole,aza-dibenzofuran, aza-dibenzothiophene, azadibenzoselenophene, andcombinations thereof, which are optionally further substituted with oneor more groups selected from hydrogen, deuterium, halide, alkyl,cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl,alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl,carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof, and wherein thesubstitution is optionally fused to the carbazole, dibenzofuran,dibenzothiophene, dibenzoselenophene, aza-carbazole, aza-dibenzofuran,aza-dibenzothiophene or azadibenzoselenophene group.

In one embodiment, the organic layer is an emissive layer and thecompound of Formula I is a host. In another aspect, the organic layerfurther comprises an emissive dopant.

In one embodiment, the emissive dopant is a transition metal complexhaving at least one ligand selected from the group consisting of:

wherein R_(a), R_(b), and R_(c) may represent mono, di, tri or tetrasubstitutions, wherein R_(a), R_(b), and R_(c) are independentlyselected from the group consisting of hydrogen, deuterium, halide,alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl,acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein twoadjacent substituents of R_(a), R_(b), and R_(c) are optionally joinedto form a fused ring.

In one embodiment, the emissive dopant has the formula

wherein D is a 5- or 6-membered carbocyclic or heterocyclic ring,wherein R₁, R₂, and R₃ independently represent mono, di, tri or tetrasubstitution, wherein each of R₁, R₂, and R₃ are independently selectedfrom the group consisting of hydrogen, deuterium, halide, alkyl,cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl,alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl,carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof, wherein R₁ canbe optionally linked to ring D, wherein n is 1, 2, or 3, and wherein X—Yis another ligand.

In one embodiment, the device further comprises a second organic layerthat is a non-emissive layer and the compound having Formula I is amaterial in the second organic layer.

In another embodiment, the second organic layer is a blocking layer andthe compound having Formula I is a blocking material in the secondorganic layer. In one embodiment, the second organic layer is anelectron transporting layer and the compound having the Formula I is anelectron transporting material in the second organic layer.

In one embodiment, the first device is a consumer product. In anotherembodiment, the first device is an organic light-emitting device. In oneembodiment, the first device comprises a lighting panel.

Device Examples

The exemplary devices described below may advantageously utilize thecompounds of Formula I, and are not intended to be limiting. Thestructures of the materials used in the device examples are shown below:

All example devices were fabricated by high vacuum (<10⁻⁴ Torr) thermalevaporation (VTE). The anode electrode is 800 Å of indium tin oxide(ITO). The cathode consisted of 10 Å of LiF followed by 1,000 Å of Al.All devices are encapsulated with a glass lid sealed with an epoxy resinin a nitrogen glove box (<1 ppm of H₂O and O₂) immediately afterfabrication, and a moisture getter was incorporated inside the package.

The organic stack of the OLED device used in the Examples andComparative Device Examples has the following structure: from the ITOsurface, 100 Å of LG101 (purchased from LG Chem) as the hole injectionlayer, 300 Å of NPD as the hole transporting layer (HTL), 300 Å of acompound of Formula I (or comparative compound CC-1 or CC2) doped with15 weight percent of Dopant D as the emissive layer (EML), 50 Å ofCompound BL as the Blocking Layer (BL) and 400 Å of Alq as the electrontransport layer (ETL). A schematic exemplary device structure isdepicted in FIG. 4.

TABLE 3 Summary of Device Data At 1000 nits At 1931 CIE λ_(max) LE EQEPE 20 mA/cm² Example Host Dopant BL x y [nm] [cd/A] [%] [lm/W] LT_(80%)[h] Device Compound Dopant Compound 0.173 0.3913 474 44.7 19.8 24 11.4Example 1 1 D BL Device Compound Dopant Compound 0.1737 0.3887 474 4419.5 23.4 16.0 Example2 3 D BL Device Compound Dopant Compound 0.17810.4034 476 44.3 19.2 22.9 24.2 Example 3 4 D BL Comparative CC-1 DopantCompound 0.1803 0.3877 474 23.7 10.5 10.3 18.5 Device D BL Example 1Comparative CC-2 Dopant Compound 0.1853 0.3986 474 24.3 10.5 9.8 0.01Device D BL Example 2

Table 3 contains a summary of the device data. The luminous efficiency(LE), external quantum efficiency (EQE) and power efficiency (PE) weremeasured at 1000 nits, while the lifetime (LT_(80%)) was defined as thetime required for the device to decay to 80% of its initial luminanceunder a constant current density of 20 mA/cm². Compared to the devicesbased on comparative examples, i.e. Comparative Device Examples 1 and 2,the devices based on compounds of Formula I, i.e. Device Examples 1 to3, exhibit two-fold improvement in device efficiencies (LE, EQE and PE),while maintaining comparable or even extended operational lifetimes. Theimprovement in device performance is attributable to the improved chargeinjection and transport of the asymmetric compounds of Formula I, whichhelps to balance charge fluxes. Without being bound by theory, it isbelieved that the balanced electron/hole fluxes spread the chargerecombination zone, which preserves a high efficiency at high brightnessby suppressing or reducing exciton quenching. An expanded chargerecombination zone also extends the device lifetime by allowing a largerpopulation of molecules to have charge transport, exciton formation, andlight emission roles. Based on the HOMO/LUMO levels reported in Table 2,compounds of Formula I can also be used in the hole blocking layers.Since compounds of Formula I can serve both as hosts and hole blockingmaterials in the hole blocking layers, incorporation of compounds ofFormula I into optical devices is expected to reduce device fabricationcosts.

Combination with Other Materials

The materials described herein as useful for a particular layer in anorganic light emitting device may be used in combination with a widevariety of other materials present in the device. For example, emissivedopants disclosed herein may be used in conjunction with a wide varietyof hosts, transport layers, blocking layers, injection layers,electrodes and other layers that may be present. The materials describedor referred to below are non-limiting examples of materials that may beuseful in combination with the compounds disclosed herein, and one ofskill in the art can readily consult the literature to identify othermaterials that may be useful in combination.

HIL/HTL:

A hole injecting/transporting material to be used in the presentinvention is not particularly limited, and any compound may be used aslong as the compound is typically used as a hole injecting/transportingmaterial. Examples of the material include, but not limit to: aphthalocyanine or porphryin derivative; an aromatic amine derivative; anindolocarbazole derivative; a polymer containing fluorohydrocarbon; apolymer with conductivity dopants; a conducting polymer, such asPEDOT/PSS; a self-assembly monomer derived from compounds such asphosphonic acid and sliane derivatives; a metal oxide derivative, suchas MoO_(x); a p-type semiconducting organic compound, such as1,4,5,8,9,12-Hexaazatriphenylenehexacarbonitrile; a metal complex, and across-linkable compounds.

Examples of aromatic amine derivatives used in HIL or HTL include, butnot limit to the following general structures:

Each of Ar¹ to Ar⁹ is selected from the group consisting aromatichydrocarbon cyclic compounds such as benzene, biphenyl, triphenyl,triphenylene, naphthalene, anthracene, phenalene, phenanthrene,fluorene, pyrene, chrysene, perylene, azulene; group consisting aromaticheterocyclic compounds such as dibenzothiophene, dibenzofuran,dibenzoselenophene, furan, thiophene, benzofuran, benzothiophene,benzoselenophene, carbazole, indolocarbazole, pyridylindole,pyrrolodipyridine, pyrazole, imidazole, triazole, oxazole, thiazole,oxadiazole, oxatriazole, dioxazole, thiadiazole, pyridine, pyridazine,pyrimidine, pyrazine, triazine, oxazine, oxathiazine, oxadiazine,indole, benzimidazole, indazole, indoxazine, benzoxazole, benzisoxazole,benzothiazole, quinoline, isoquinoline, cinnoline, quinazoline,quinoxaline, naphthyridine, phthalazine, pteridine, xanthene, acridine,phenazine, phenothiazine, phenoxazine, benzofuropyridine,furodipyridine, benzothienopyridine, thienodipyridine,benzoselenophenopyridine, and selenophenodipyridine; and groupconsisting 2 to 10 cyclic structural units which are groups of the sametype or different types selected from the aromatic hydrocarbon cyclicgroup and the aromatic heterocyclic group and are bonded to each otherdirectly or via at least one of oxygen atom, nitrogen atom, sulfur atom,silicon atom, phosphorus atom, boron atom, chain structural unit and thealiphatic cyclic group. Wherein each Ar is further substituted by asubstituent selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof.

In one aspect, Ar¹ to Ar⁹ is independently selected from the groupconsisting of:

k is an integer from 1 to 20; X¹ to X⁸ is C (including CH) or N; Ar¹ hasthe same group defined above.

Examples of metal complexes used in HIL or HTL include, but not limit tothe following general formula:

M is a metal, having an atomic weight greater than 40; (Y¹-Y²) is abidentate ligand, Y¹ and Y² are independently selected from C, N, O, P,and S; L is an ancillary ligand; m is an integer value from 1 to themaximum number of ligands that may be attached to the metal; and m+n isthe maximum number of ligands that may be attached to the metal.

In one aspect, (Y¹-Y²) is a 2-phenylpyridine derivative.

In another aspect, (Y¹-Y²) is a carbene ligand.

In another aspect, M is selected from Ir, Pt, Os, and Zn.

In a further aspect, the metal complex has a smallest oxidationpotential in solution vs. Fc⁺/Fc couple less than about 0.6 V.

Host:

The light emitting layer of the organic EL device of the presentinvention preferably contains at least a metal complex as light emittingmaterial, and may contain a host material using the metal complex as adopant material. Examples of the host material are not particularlylimited, and any metal complexes or organic compounds may be used aslong as the triplet energy of the host is larger than that of thedopant. While the Table below categorizes host materials as preferredfor devices that emit various colors, any host material may be used withany dopant so long as the triplet criteria is satisfied.

Examples of metal complexes used as host are preferred to have thefollowing general formula:

M is a metal; (Y³-Y⁴) is a bidentate ligand, Y³ and Y⁴ are independentlyselected from C, N, O, P, and S; L is an ancillary ligand; m is aninteger value from 1 to the maximum number of ligands that may beattached to the metal; and m+n is the maximum number of ligands that maybe attached to the metal.

In one aspect, the metal complexes are:

(O—N) is a bidentate ligand, having metal coordinated to atoms O and N.

In another aspect, M is selected from Ir and Pt.

In a further aspect, (Y³-Y⁴) is a carbene ligand.

Examples of organic compounds used as host are selected from the groupconsisting aromatic hydrocarbon cyclic compounds such as benzene,biphenyl, triphenyl, triphenylene, naphthalene, anthracene, phenalene,phenanthrene, fluorene, pyrene, chrysene, perylene, azulene; groupconsisting aromatic heterocyclic compounds such as dibenzothiophene,dibenzofuran, dibenzoselenophene, furan, thiophene, benzofuran,benzothiophene, benzoselenophene, carbazole, indolocarbazole,pyridylindole, pyrrolodipyridine, pyrazole, imidazole, triazole,oxazole, thiazole, oxadiazole, oxatriazole, dioxazole, thiadiazole,pyridine, pyridazine, pyrimidine, pyrazine, triazine, oxazine,oxathiazine, oxadiazine, indole, benzimidazole, indazole, indoxazine,benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline,cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine,pteridine, xanthene, acridine, phenazine, phenothiazine, phenoxazine,benzofuropyridine, furodipyridine, benzothienopyridine,thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine;and group consisting 2 to 10 cyclic structural units which are groups ofthe same type or different types selected from the aromatic hydrocarboncyclic group and the aromatic heterocyclic group and are bonded to eachother directly or via at least one of oxygen atom, nitrogen atom, sulfuratom, silicon atom, phosphorus atom, boron atom, chain structural unitand the aliphatic cyclic group. Wherein each group is furthersubstituted by a substituent selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof.

In one aspect, host compound contains at least one of the followinggroups in the molecule:

R¹ to R⁷ is independently selected from the group consisting ofhydrogen, deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl,alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl,alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester,nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, andcombinations thereof, when it is aryl or heteroaryl, it has the similardefinition as Ar's mentioned above.

k is an integer from 0 to 20.

X¹ to X⁸ is selected from C (including CH) or N.

Z¹ and Z² is selected from NR¹, O, or S.

HBL:

A hole blocking layer (HBL) may be used to reduce the number of holesand/or excitons that leave the emissive layer. The presence of such ablocking layer in a device may result in substantially higherefficiencies as compared to a similar device lacking a blocking layer.Also, a blocking layer may be used to confine emission to a desiredregion of an OLED.

In one aspect, compound used in HBL contains the same molecule or thesame functional groups used as host described above.

In another aspect, compound used in HBL contains at least one of thefollowing groups in the molecule:

k is an integer from 0 to 20; L is an ancillary ligand, m is an integerfrom 1 to 3.

ETL:

Electron transport layer (ETL) may include a material capable oftransporting electrons. Electron transport layer may be intrinsic(undoped), or doped. Doping may be used to enhance conductivity.Examples of the ETL material are not particularly limited, and any metalcomplexes or organic compounds may be used as long as they are typicallyused to transport electrons.

In one aspect, compound used in ETL contains at least one of thefollowing groups in the molecule:

R¹ is selected from the group consisting of hydrogen, deuterium, halide,alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl,acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof, when it is arylor heteroaryl, it has the similar definition as Ar's mentioned above.

Ar¹ to Ar³ has the similar definition as Ar's mentioned above.

k is an integer from 0 to 20.

X¹ to X⁸ is selected from C (including CH) or N.

In another aspect, the metal complexes used in ETL contains, but notlimit to the following general formula:

(O—N) or (N—N) is a bidentate ligand, having metal coordinated to atomsO, N or N, N; L is an ancillary ligand; m is an integer value from 1 tothe maximum number of ligands that may be attached to the metal.

In any above-mentioned compounds used in each layer of the OLED device,the hydrogen atoms can be partially or fully deuterated.

In addition to and/or in combination with the materials disclosedherein, many hole injection materials, hole transporting materials, hostmaterials, dopant materials, exiton/hole blocking layer materials,electron transporting and electron injecting materials may be used in anOLED. Non-limiting examples of the materials that may be used in an OLEDin combination with materials disclosed herein are listed in Table 4below. Table 4 lists non-limiting classes of materials, non-limitingexamples of compounds for each class, and references that disclose thematerials.

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EXPERIMENTAL

Chemical abbreviations used throughout this document are as follows: dbais dibenzylideneacetone, EtOAc is ethyl acetate, dppf is1,1′-bis(diphenylphosphino)ferrocene, DCM is dichloromethane, SPhos isdicyclohexyl(2′,6′-dimethoxy-[1,1′-biphenyl]-3-yl)phosphine, THF istetrahydrofuran.

Synthesis of Compound 1

Into a suspension of 2-bromotriphenylene (7.28 g, 23.70 mmol) in ether(50 mL) was added n-butyllithium solution in hexane (14.81 mL, 23.70mmol) dropwise at −78° C. The suspension was gradually warmed to 0° C.and stirred for 3 hours to yield a solution of triphenylenyllithium. Ina separate flask a solution of 3-bromophenyllithium was prepared bydropwise addition of n-butyllithium solution in hexane (14.81 mL, 23.70mmol) into a solution of 1,3-dibromobenzene (2.87 mL, 23.70 mmol) inether (50 mL). The solution was stirred at this temperature for 2.5hours before being transferred into a solution of dichlorodiphenylsilane(4.88 mL, 23.70 mmol) in ether (30 mL) at −78° C. After stirring foranother 2 h, the triphenylenyllithium solution prepared above wasintroduced dropwise into the flask containing the dichlorophenylsilane.The reaction mixture was allowed to gradually warm to room temperatureand was stirred overnight. The mixture was quenched with water and theorganic phase was isolated. Upon evaporation of the solvent, the residuewas purified by column chromatography on silica gel with hexane/DCM(85/15, v/v) as eluent to yield(3-bromophenyl)diphenyl(triphenylen-2-yl)silane (8.5 g, 75%) as a whitepowder.

A solution of dibenzo[b,d]thiophen-4-ylboronic acid (1.573 g, 6.90mmol), (3-bromophenyl)diphenyl(triphenylen-2-yl)silane (3, 5.30 mmol),Pd₂(dba)₃ (0.097 g, 0.106 mmol), SPhos (0.087 g, 0.212 mmol) and K₃PO₄(3.38 g, 15.91 mmol) in toluene (50 mL) and water (7 mL) was stirred at100° C. under nitrogen overnight. After cooling to room temperature, theorganic phase was isolated, the aqueous phase was extracted with DCM,and the combined organic solution was dried over Na₂SO₄. Uponevaporation of the solvent, the residue was purified by columnchromatography on silica gel with hexane/dichlromethane (9/1 to 8.5/1.5,v/v) as eluent to yield Compound 1 (2.4 g, 68%) as a white solid.

Synthesis of Compound 2

A solution of (3-bromophenyl)diphenyl(triphenylen-2-yl)silane (2.9 g,5.13 mmol), dibenzo[b,d]furan-4-ylboronic acid (1.196 g, 5.64 mmol),Pd₂(dba)₃ (0.094 g, 0.10 mmol), SPhos (90 mg, 0.22 mmol) and K₃PO₄ (2.72g, 12.82 mmol) in toluene (150 mL) and water (10 mL) was refluxed undernitrogen overnight. After evaporation off the solvent, the residue waspurified by column chromatography on silica gel with hexane/DCM (4/1,v/v) as eluent to yield Compound 2 (1.5 g, 44%) as a white solid.

Synthesis of Compound 3

A mixture of (3-bromophenyl)diphenyl(triphenylen-2-yl)silane (3.52 g,6.22 mmol), 9H-carbazole (1.249 g, 7.47 mmol), Pd₂(dba)₃ (0.114 g, 0.124mmol), SPhos (0.102 g, 0.249 mmol), and sodium tert-butoxide (1.794 g,18.67 mmol) in m-xylene (100 mL) was refluxed under nitrogen overnight.After cooling to room temperature, it was filtered through a plug ofCelite®. The organic solution was concentrated, and the residue waspurified by column chromatography on silica gel with hexane/DCM (85/15,v/v) as eluent and precipitation in methanol to yield Compound 3 (3.5 g,86%) as a white powder.

Synthesis of Compound 4

A mixture of (3-bromophenyl)diphenyl(triphenylen-2-yl)silane (3 g, 5.30mmol), 9H-3,9′-bicarbazole (2.116 g, 6.37 mmol), Pd₂(dba)₃ (0.097 g,0.106 mmol), SPhos (0.087 g, 0.212 mmol), and sodium tert-butoxide(1.529 g, 15.91 mmol) in m-xylene (100 mL) was refluxed under nitrogenat 165° C. overnight. After cooling to room temperature, it was filteredthrough a short plug of Celite®. Upon evaporation off the solvent, theresidue was purified by column chromatography on silica gel withhexane/DCM(8/2 to 3/1, v/v) as eluent to yield Compound 4 (4.0 g, 92%)as a white solid.

Synthesis of Compound 5

A solution of (3-bromophenyl)diphenyl(triphenylen-2-yl)silane (2.5 g,4.42 mmol), 9-phenyl-9H,9′H-3,3′-bicarbazole (1.806 g, 4.42 mmol),Pd₂(dba)₃ (0.081 g, 0.088 mmol), SPhos (0.073 g, 0.177 mmol) and sodiumtert-butoxide (1.274 g, 13.26 mmol) in m-xylene (80 mL) was refluxedunder nitrogen overnight. After cooling to room temperature, it waspassed through a short plug of Celite®. Upon evaporation off thesolvent, the residue was purified by column chromatography on silica gelwith hexane/DCM (4/1 to 3/2, v/v) as eluent to yield Compound 5 as awhite powder.

Synthesis of Comparative Compound 1 (CC-1)

2-Bromotriphenylene (3.4 g, 11.1 mmol) was dissolved in Et₂O (100 mL)and cooled to −78° C. before n-BuLi (4.9 mL, 12.1 mmol) was addeddropwise. The reaction mixture was allowed to slowly warm to −0° C. andstirred for 30 minutes before it was re-cooled to −78° C.Diphenyldichlorosilane (1.1 mL, 5.3 mmol) in 20 mL of Et₂O was addeddropwise to the reaction mixture. After slowly warming to roomtemperature overnight the thick mixture was refluxed for 3 h. Aftercooling to room temperature, 300 mL of water was added with rapidstirring and the precipitate was filtered from the biphasic mixture,washing with Et₂O. The solid was dissolved in DCM and filtered through aplug of silica gel on a frit. Removal of the solvent yielded CC-1 (2.4g, 72%) as a white solid.

Synthesis of Comparative Compound 2 (CC-2)

2-Bromotriphenylene (5.5 g, 14.3 mmol) was dissolved in THF (50 mL) andcooled to −78° C. before n-BuLi (5.7 mL, 14.3 mmol) was added dropwise.The reaction mixture was allowed to slowly warm to −30° C. before it wasrecooled to −78° C. Chlorotriphenylsilane (3.8 g, 13.0 mmol) wasdissolved in 20 mL of THF and added dropwise to the reaction mixturewhich was subsequently allowed to slowly warm to room temperatureovernight and further heated to 40° C. for 2 h. After cooling to roomtemperature, the reaction was quenched with MeOH and NH₄Cl (aq.),extracted three times with EtOAc (50 mL), dried and rotovapped to give7.8 g of a yellow solid. The crude material was chromatographed onsilica hexane/DCM (9/1, v/v) as eluent. Recrystallization fromDCM/hexane gave CC-2 (5.5 g, 87%) as a white crystalline solid.

It is understood that the various embodiments described herein are byway of example only, and are not intended to limit the scope of theinvention. For example, many of the materials and structures describedherein may be substituted with other materials and structures withoutdeviating from the spirit of the invention. The present invention asclaimed may therefore include variations from the particular examplesand preferred embodiments described herein, as will be apparent to oneof skill in the art. It is understood that various theories as to whythe invention works are not intended to be limiting.

The invention claimed is:
 1. A compound having formula:

wherein Ar and Ar′ are independently selected from the group consistingof phenyl, biphenyl, naphthalene, dibenzothiophene and dibenzofuran,which are optionally further substituted; Z is selected from Si and Ge;L is a single bond or comprises an aryl or heteroaryl group having from5-20 carbon atoms, which is optionally further substituted; A is a groupdirectly bonded to Z and is selected from the group consisting oftriphenylene, tetraphenylene, pyrene, naphthalene, fluoranthene,chrysene, phenanthrene, azatriphenylene, azatetraphenylene, azapyrene,azanaphthalene, azafluoranthene, azachrysene, azaphenanthrene, andcombinations thereof, which are optionally further substituted with oneor more groups selected from the group consisting of hydrogen,deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, aryl,aryloxy, and combinations thereof; B is a group selected from the groupconsisting of carbazole, dibenzoselenophene, aza-carbazole,aza-dibenzofuran, aza-dibenzothiophene, azadibenzoselenophene, andcombinations thereof, which are optionally further substituted with oneor more groups selected from hydrogen, deuterium, halide, alkyl,cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl,alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl,carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein thesubstitution is optionally fused to the carbazole, dibenzoselenophene,aza-carbazole, aza-dibenzofuran, aza-dibenzothiophene oraza-dibenzoselenophene group wherein when B is carbazole, the carbazolegroup is connected to L through a ring carbon.
 2. The compound of claim1, wherein A is

wherein K₁ to K₁₂ are independently selected from N and C—R′; andwherein R′ is selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, aryl, aryloxy, andcombinations thereof, wherein R′ does not exist on one of K₁ to K₄ whensaid one of K₁ to K₄ is bonded to Z is C.
 3. The compound of claim 1,wherein B is selected from the group consisting of:

wherein X₁-X₁₅ are independently selected from the group consisting of Nand C—R″, wherein R″ is selected from a group consisting of hydrogen,deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy,aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl,aryl, heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof, wherein R″ does not exist on one of X₁ to X₈ when said one ofX₁ to X₈ that is bonded to L is C; and wherein Y₁ and Y₂ areindependently selected from the group consisting of O, S, and Se.
 4. Thecompound of claim 1, wherein A is selected from the group consisting of:


5. The compound of claim 1, wherein A is selected from the groupconsisting of:


6. The compound of claim 1, wherein B is selected from the groupconsisting of:

wherein Y₁ is selected from the group consisting of O, S, and Se;wherein R is selected from the group consisting of hydrogen, deuterium,halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy,amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acids, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof.
 7. The compound of claim 1, wherein L is independently selectedfrom the group consisting of:


8. The compound of claim 1, wherein A is tripheynylene.
 9. The compoundof claim 1, wherein A is pyrene.
 10. The compound of claim 1, wherein Arand Ar′ are phenyl.
 11. The compound of claim 1, wherein L is phenyl.12. The compound of claim 1, whereto the compound is selected from thegroup consisting of:


13. A first device comprising an organic light-emitting device, furthercomprising: an anode; a cathode; and an organic layer, disposed betweenthe anode and the cathode, comprising a compound having the formula:

wherein Ar and Ar′ are independently selected from the group consistingof phenyl, biphenyl, naphthalene, dibenzothiophene and dibenzofuran,which are optionally further substituted; Z is selected from Si and Ge;L is a single bond or comprises an aryl or heteroaryl group having from5-20 carbon atoms, which is optionally further substituted; A is a groupdirectly bonded to Z and is selected from the group consisting oftriphenylene, tetraphenylene, pyrene, naphthalene, fluoranthene,chrysene, phenanthrene, azatriphenylene, azatetraphenylene, azapyrene,azanaphthalene, azafluoranthene, azachrysene, azaphenanthrene, andcombinations thereof, which are optionally further substituted with oneor more groups selected from the group consisting of hydrogen,deuterium, halide, alkyl, cycloalkyl, heteroalkyl, arylalkyl, aryl,aryloxy, and combinations thereof; B is a group selected from the groupconsisting of carbazole, dibenzoselenophene, aza-carbazole,aza-dibenzofuran, aza-dibenzothiophene, azadibenzoselenophene, andcombinations thereof, which are optionally further substituted with oneor more groups selected from hydrogen, deuterium, halide, alkyl,cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl,alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl,carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein thesubstitution is optionally fused to the carbazole, dibenzoselenophene,aza-carbazole, aza-dibenzofuran, aza-dibenzothiophene orazadibenzoselenophene group wherein when B is carbazole, the carbazolegroup is connected to L through a ring carbon.
 14. The first device ofclaim 13, wherein the organic layer is an emissive layer and thecompound of Formula I is a host.
 15. The first device of claim 13,wherein the organic layer further comprises an emissive dopant.
 16. Thefirst device of claim 15, wherein the emissive dopant is a transitionmetal complex having at least one ligand selected from the groupconsisting of:

wherein R_(a), R_(b), and R_(c) may represent mono, di, tri or tetrasubstitutions; wherein R_(a), R_(b), and R_(c) are independentlyselected from the group consisting of hydrogen, deuterium, halide,alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino,silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl,acyl, carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof; and wherein twoadjacent substituents of R_(a), R_(b), and R_(c) are optionally joinedto form a fused ring.
 17. The first device of claim 15, wherein theemissive dopant has the formula

wherein D is a 5- or 6-membered carbocyclic or heterocyclic ring;wherein R₁, R₂, and R₃ independently represent mono, di, tri or tetrasubstitution; wherein each of R₁, R₂, and R₃ are independently selectedfrom the group consisting of hydrogen, deuterium, halide, alkyl,cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl,alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl,carbonyl, carboxylic acids, ester, nitrile, isonitrile, sulfanyl,sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein R₁ canbe optionally linked to ring D; wherein n is 1, 2, or 3; and wherein X—Yis another ligand.
 18. The first device of claim 13, wherein the devicefurther comprises a second organic layer that is a non-emissive layerand the compound having Formula I is a material in the second organiclayer.
 19. The first device of claim 18, wherein the second organiclayer is a blocking layer and the compound having Formula I is ablocking material in the second organic layer.
 20. The first device ofclaim 18, wherein the second organic layer is an electron transportinglayer and the compound having the Formula I is an electron transportingmaterial in the second organic layer.
 21. The first device of claim 13,wherein the first device is a consumer product.
 22. The first device ofclaim 13, wherein the first device is an organic light-emitting device.23. The first device of claim 14, wherein the first device comprises alighting panel.